DOMS (Delayed-Onset Muscle Soreness)

Formula

Example

Athlete returns from a 2-week travel break and hits a heavy leg day: 5x5 back squat, 4x8 Romanian deadlift, 3x12 walking lunges. Day-of: feels normal. Day +1 morning: stairs are uncomfortable. Day +2: peak soreness — Hooper soreness axis 6/7, sitting down is a project. Day +4: residual tightness only. The same session repeated weekly produces almost no DOMS by week 3 — the repeated-bout effect.

How Afitpilot Uses This

We don't measure DOMS directly. The Hooper-Mackinnon soreness axis (captured daily via the readiness prompt) is our proxy, and it feeds into the Hooper Index trend on the coach drawer and athlete Profile view. We deliberately do not auto-modify sessions from a single high soreness score — DOMS is descriptive, not diagnostic. Practical implication: a Hooper soreness of 6-7 for 3+ consecutive days on the same body region after a programme change is a flag to ease the next session for that region, not a verdict on the plan. First-week-of-block soreness is expected and the plan generator already front-loads stimulus knowing it will fade by week 2-3 via the repeated-bout effect.

DOMS — what triggers what

Known Limitations

• •DOMS is not a measure of muscle growth or training effectiveness. The Schoenfeld and Contreras (2013) review is explicit: soreness correlates poorly with hypertrophy outcomes. "Crushing it" by soreness standard often just means "did something new."
• •DOMS habituates fast. The repeated-bout effect means the same session that produced 7/7 soreness in week 1 produces 2/7 by week 3 — without any reduction in actual training stimulus. Tracking soreness as a progress signal is misleading after the first week of a new block.
• •Soreness is self-reported through a 1-7 axis. Two athletes with identical CK levels can report soreness 3 vs 6 based on pain tolerance, mood, and attention. Trend within an athlete is the only reliable read.
• •Severe DOMS (Hooper soreness 6-7 for 4+ days, especially with dark urine, swelling, or weakness disproportionate to the session) can mask exertional rhabdomyolysis — a medical issue, not a training one. The app does not screen for this; athletes with these symptoms should see a clinician.
• •DOMS distribution is uneven across exercise types. Eccentric-heavy and novel-range work produces disproportionate soreness; steady-state cardio and well-grooved compound lifts produce very little even at high stress. Two sessions with identical AU can produce wildly different soreness.

Science Context

The mechanical-damage model of DOMS dates to Armstrong (1984) and Newham (1988): unaccustomed eccentric contractions disrupt sarcomere Z-lines, triggering an inflammatory repair cascade that peaks 24-72h post-exercise. The repeated-bout effect — rapid attenuation of soreness with the same stimulus — was formalised by McHugh et al. (1999) and is one of the most reliably reproduced phenomena in exercise science. Modern reviews (Schoenfeld & Contreras 2013; Hyldahl et al. 2017) consistently find that DOMS magnitude correlates weakly with hypertrophy and strength gains, undermining the popular "sore = grew" heuristic. The practical translation Afitpilot uses: capture soreness as a recovery-context signal via Hooper, use the trend over days to inform plan adjustments, and never treat it as a training-quality scorecard.

Related Terms

• ReadinessThe athlete's arrival state before training — how rested, sore, and mentally prepared you are when you walk in. Readiness is the third layer of Afitpilot's load model (alongside internal load and external load), capturing context that load metrics alone cannot.
• Active RecoveryLow-intensity movement performed on a non-training day or between hard sessions, with the explicit goal of accelerating recovery rather than accumulating training stress. Active recovery sits in the narrow band between complete rest and easy aerobic training — light enough that it doesn't add to fatigue, structured enough that it produces a recovery benefit. Common examples: easy walking, light cycling, a slow swim, mobility work, restorative yoga.
• Hooper IndexA 5-35 readiness score that sums five 1-7 self-ratings: sleep quality, muscle soreness, fatigue, mood, and stress. Lower is better — 5 is "feel great on every axis," 35 is "every axis at its worst." Captured once per calendar day via the daily prompt.
• HRV (Heart Rate Variability)The beat-to-beat variation in time between heartbeats, measured in milliseconds. HRV is a window into autonomic nervous system balance — a relatively high, stable morning HRV suggests parasympathetic dominance and good recovery; a depressed or volatile HRV often signals accumulated training stress, illness, or poor sleep before subjective fatigue catches up.
• NEAT (Non-Exercise Activity Thermogenesis)All the energy you burn moving outside of structured training and basal metabolism — walking to the kitchen, fidgeting, standing, climbing stairs, doing chores, pacing on phone calls. NEAT is the largest and most variable component of daily energy expenditure for most people, often dwarfing the calories burned in a typical training session. For athletes, it is also the most under-counted source of cumulative recovery debt.